Download IPR-06-05

Abstract
Within the frame of the LTDE project (in situ studying of diffusion and sorption
processes over longer time-scales) a functionality test with short-lived radionuclides has
been performed. This report describes the performance and procedures of the
functionality test together with the obtained results.
The main objectives of the test were to test injection and sampling procedures as well as
to check the functionality of individual systems such as, for example, circulation
equipment, pressure regulator, sensors, on-line measurements and alarms. It could be
concluded from the functionality test that all systems worked overall as expected. Some
minor adjustments and modifications are proposed to increase the functionality prior to
a future long term test. Also, the injection and sampling procedures concerning the
tracers functioned as planned.
Another objective of the test was to investigate if sorption, in terms of decreasing tracer
concentration in the test section, could be monitored. Both non-sorbing and sorbing
tracers were used. The following trend could be observed: Ca(II) ≤ I(-I) < Np(V) <
Cd(II) < Cs(I) < Lu(III) < Hf(IV), where no sorption of Ca(II) is observed and I(-I)
shows a weak sorption. The sorption results are discussed in relation to speciation
calculations for the different species. Surface sorption coefficients and matrix sorption
coefficients are evaluated for a batch sorption and a sorption-diffusion model
respectively. However, the sorption data presented in this report should be regarded as
indicative rather than absolute. Further, the results from the tracer experiment indicate
that sufficient mixing of the tracer solution(s) in the test section will be obtained for a
long term diffusion experiment as planned. Short-time experiments with duration of
hours to days are however unsuitable with the present borehole configuration.
The duration of the functionality test was four weeks. pH and redox potentials were
continuously monitored with an electrochemical flow cell developed for measurements
at high pressures. Furthermore, continuous pressure monitoring and additional sampling
and analysis for tracers in the first guard section, particles, microbes, radon, sorption of
tracers on tubing and groundwater chemical composition was done. The results are
shown and discussed in the report.
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